The present invention relates to a color photographic light-sensitive material for printing use and more particularly to the color photographic light-sensitive material for printing use which is excellent in gradation characteristics.
Generally speaking, in a negative-positive type color photography, a photographic object is photographed on a color negative film through a camera, so that a negative image may be produced. The resulting negative image is printed on a sheet of color printing paper by a printer, so that a color print of the image may be produced to be a final object of appreciation.
One of the essential factors in controlling the quality of such a color print as described above is the gradation characteristics of a color printing paper.
If the gradation characteristics of a color printing paper are improper, that is, for example, if the gradation of the paper is too hard, the image printed out on the paper will lack the proper image representation especially in the low and high density portions of the printed image; and if the gradation is too soft, the image printed out on the paper will come out dull and fuzzy. The resulting color print came out in either case is not satisfactory in quality.
A color print will not come out satisfactorily in quality even if only the gradation characteristics of a single silver halide emulsion layer are satisfactory. In a substractive color photography, the three colors, cyan, magenta and yellow, are to be well-balanced together from the high-light portions to the shadow portions of a scene.
For example, if the garadation in the high density portions of a magenta color developing layer is relatively softer than those of the other color developing layers, the shadow portions of the layer will be changed from black into greenish black, and if the gradation thereof is relatively too harder, the shadow portion thereof will be changed into redish black. Anyway, a poor color print in color reproductivity will come out in either case. As described above, the gradation characteristics of a color photographic light-sensitive material for color printing use are indispensable from the viewpoints of both tone and color reproductivity. It is therefore demanded to develop a technique capable of enjoying a proper gradation.
One of the most well-known techniques for controlling gradations is to change an amount of silver to be coated on. This technique has such a disadvatage that a maximum density is varied, though this is the easiest way to control gradations. Therefore, this technique is merely used for a fine adjustment or the like.
Another well-known technique is that one and the same layer or separate layers are added with a plurality of silver halide grains which are harder than those in a desired gradation and have the same color sensitivity with and the different photographic sensitivity from each other. This is a technique generally known in the art. According to this technique, it seems to be able to produce any gradation theoretically, however, when applying this technique practically to a commercial production, the practical applicability thereof is limited because of the restrictions in manufacturing facility and costs or the like. Any manufacturing effect may be unable to enjoy if this technique is solely used.
There are well-known gradation adjusting techniques to be used in a process of preparing a light-sensitive silver halide emulsion. They include, for example, a hardening technique in which a metal ion dope such as that of rhodium, iridium or the like is used in a physically ripening process; a technique in which the conditions desired for producing silver halide grains are suitably selected from, for example, a single-jet precipitation process that is suitable for making a soft-type emulsion double-jet precipitation process that is suitable for making a hard-type emulsion and the values of pAg, pH and composition distribution of a silver halide each in producung grains; a technique in which the conditions desired for a chemical sensitization are selected; and the like. The desired gradation may be obtained by using the above-mentioned techniques independently or in combination, however, in almost all cases, the deteriorations will be caused in other photographic characteristics such as sensitivity, fog, reciprocity law failure, latent-image stability, pressure resistance, and the like, or in stability in manufacture, and it requires much trouble to find out the satisfactory conditions in either case. The above-mentioned technique may display only a limited effect if it is put into practical use.
For producing colors in a subtractive color process with a silver halide photographic light sensitive material including a color photographic light sensitive material for printing use, there uses a yellow coupler, a magenta coupler and a cyan coupler capable of forming a yellow dye image, a magenta dye image and a cyan dye image respectively through a coupling reaction thereof to the oxidation products of an aromatic primary amine color developing agent. A gradation may anyway be changed by selecting the kinds of the above-mentioned couplers or the substituents thereof, however, this technique is also difficult to put into practical use, because of the undesirable changes caused in the order characteristics of the light sensitive material, such as the spectral characteristics of the dye images, the stability of the dye images.
Further, there are, for example, a description of a technique for softening a high-light portion by selecting a suitable high boiling solvent for a coupler in Japanese Patent O.P.I. Publication No. 40550/1983; and another description of a gradation adjusting technique in which a high boiling solvent is selected and a catechol derivative is used in Japanese Patent Application No. 213161/1984. In these techniques, it was found that some specific density area of some specific emulsion layer was effectivly improved but the overall gradations, the gradation balance and the like were not satisfactorily improved, though the techniques did work anyhow.
After the inventors were devoted to their studies by making use of the above-mentioned techniques, they found that they reached the reasonably satisfiable levels of the gradations and the balance thereof as far as both of a blue-sensitive emulsion layer and a red-sensitive emulsion layer concerned, but they did not reach any satisfiable level in matching with a green-sensitive emulsion layer. Resultantly, they failed to obtain any color photographic light sensitive material for printing use which is satisfiable in gradation characteristics.
In the above-mentioned techniques, it was difficult to manufacture inexpensively and stably any color photographic light sensitive material for printing use which is excellent in gradation and other photographic characteristics, as described above.